DCoE Director Explains Science Behind PTSD

Navy Capt. Paul S. Hammer, Defense Centers of Excellence for Psychological Health & Traumatic Brain Injury
One Veteran's Delayed Diagnosis

If you were to ask random strangers, “What is the most important organ in the human body,” what answers do you think you might get? Many people would say the heart and lungs, but for most it would probably be the brain. The brain’s role is central in our lives but that’s often overlooked or taken for granted until the brain is impacted by illness or injury.

Like any other organ or organ system in the body, it’s important to understand what the underlying problem is in order to effectively treat it. This is particularly true when we think about an individual with posttraumatic stress disorder (PTSD).  

You need to know the science.

There are three brain structures that play key roles in the science behind PTSD. They are the amygdala, hippocampus and prefrontal cortex.

The amygdala is the stress evaluator. It continuously monitors all situations for danger and decides when to react. The sights, sounds and smells of frightening and dangerous memories are stored here. When the brain recognizes similar situations, the amygdala sends out danger signals and gets the body ready for a flight or fight response.   

The hippocampus stores and retrieves memories, everything from where you attended second grade to where you parked your car three hours ago. If your brain is a computer, the hippocampus is the hard drive.

The prefrontal cortex is the large part of the brain sitting right behind your forehead. This is the executive-functioning area responsible for rational thought and decision making. In the computer analogy this is the central processing unit running the programs.

In the moment of a traumatic experience the hippocampus frantically tries to cope and calm the amygdala alarm circuit. In some cases the hippocampus is not able to calm the amygdala, resulting in damage to the hippocampus region of the brain, which lessens the ability of the amygdala to produce calming thoughts.

With PTSD, the nerve circuits connecting the amygdala, hippocampus and prefrontal cortex aren’t working correctly. The hippocampus can’t store the memory and the prefrontal cortex can’t override the hippocampus to tell the amygdala to calm down when there is no danger.

PTSD is a cluster of symptoms that occur for at least a month or more. When someone has PTSD they persistently re-experience the traumatic event, through recurring thoughts, nightmares and flashbacks because the hippocampus is not storing memories correctly. They will also experience persistent avoidance of stimuli associated with the trauma such as connected thoughts, feelings or places because the amygdala is essentially yelling, “danger!” Additionally, a patient with PTSD will have persistent increased arousal that may cause hypervigilance, irritability, difficulty sleeping or an exaggerated tendency to be easily startled.  

As difficult as PTSD can be, the good news is that when service members and veterans seek help they can get better. The brain, like other organs, can heal. It’s a matter of working with the amygdala, hippocampus and prefrontal cortex to make the traumatic memories safe.

Increased awareness of the science behind PTSD can help reduce the barriers to care and increase the number of service members, veterans and their families who are willing to get the help they need to recover.

Posted on BrainLine May 29, 2013.

Used with permission from the Defense Centers of Excellence for Psychological Health & Traumatic Brain Injury, posted May 10, 2013 by Navy Capt. Paul S. Hammer, DCoE director.  www.dcoe.health.mil.

Comments (1)

This was very informative! It helps me to understand more, what is going on w/ my son!